The following are the “bulleted” management guidelines for western corn rootworm (WCR) in first-year corn by perceived risk area. These risk areas were determined by random soybean sweeps at the peak population of WCR beetles and from pest manager’s comments. Remember, the beetle numbers vary not only in states and counties but fields as well. It is no longer possible to determine rootworm risk to the 2000 corn. Sampling the WCR beetles in soybeans during this coming August will help one make informed decisions for the 2001 growing season. More on WCR beetle sampling in later issues.
Highest Risk - Northern Indiana:
Lowest Risk - Southern Indiana:
*For more information on WCR management guidelines on first-year corn, refer to the fact sheet Managing Corn Rootworms – 2000, which can be obtained from your county extension office or viewed on the web (http://www.entm.purdue.edu/Entomology/ext/targets/publicat.htm).
Many questions have arisen concerning Regent over the winter months. Aventis has done a good job peaking producer’s curiosity with the prospect of a “free” in-furrow, application system (“OnePass”) for their planter when agreeing to purchase 300 acres or more of product. The targeted marketing area seems to be the counties that have begun to see first-year corn rootworm damage. Obviously, this relatively new rootworm phenomenon found many producers without insecticide boxes on their planters. Also, producers contemplating a new planter purchase, but wanting to reduce costs such as granular insecticide applicators, are seriously considering this product.
Fipronil, the active ingredient of Regent, has shown to be a very active and effective insecticide in many crop and non-crop uses. However, equally important to a good chemistry, is the need for proper formulation and placement of the product. This has been fipronil’s difficulty through the year’s of testing it as a soil applied rootworm insecticide. Year’s ago in university trials, it showed great promise as a granular rootworm insecticide. Then in 1998, it was labeled and commercially available as a 80WG (wettable granular). This formulation had a tendency to clog the microtubes that delivered the product in-furrow and it readily settled out of suspension. After that fiasco, the company switched to a 4 SC for the 1999 season. With few user complaints, this appears to be the formulation they will now stay with.
University trials throughout the corn belt has shown erratic results with Regent in protecting the roots from rootworm. With little root rating data on the 4 SC formulation to compare, Regent usually protects roots better than the untreated check but provides less rootworm control than most labeled granular soil insecticides. Because of this trend, our suggestion is that this product may provide acceptable control for moderate to low populations of rootworm. At this time, we cannot recommend this product where high rootworm pressure may exist. Because fipronil is systemic in the plant, there is some control/suppression of low to moderate levels of first-generation European corn borer. How this product performs on secondary soil pests like white grub, wireworm or cutworm etc. has yet to be seen.
Regent must be applied in-furrow with the seed. Researchers believe the more gallons of carrier used at application, the better the efficacy. Do not apply Regent in less than 1 gallon of carrier per acre. It can be mixed or injected into the furrow (not 2X2) with “pop-up” fertilizer (not starter). Regent has a tendency to settle out and clog the lower hoses once the agitation system has been turned off for several hours. The 4 SC formulation supposedly reduces this problem, but it hasn’t eliminated it. Do not allow any Regent to remain in the OnePass system once planting is done or significant line clogging will be likely for next year.
Late last summer, Zeneca Ag Products and Novartis Seeds (now Syngenta) announced a new product called ProShield; a concentrate of Force insecticide (tefluthrin) attached to corn seed. Very limited supplies of NK brand seed with ProShield will be available for the 2000 growing season. The label states that “Force ST insecticide, when used at labeled rates, will protect germinating seeds and seedlings against injury by cutworm, Northern corn rootworm, seedcorn maggot, Southern corn rootworm, Western corn rootworm, white grub, and wireworms.” It is labeled for field corn, popcorn, seed corn, and sweet corn. Force ST is applied to the seed during processing and placed in sealed plastic seed bags.
Efficacy data supplied by Novartis shows promise for this seed delivered insecticide control. Our skepticism comes from the fact that universities have had little time to test the product. We cannot recommend a product on one year’s performance in independent trials. Those trials suggest that ProShield offers marginal corn rootworm larval control. Because tefluthrin is not systemic and insecticides generally have little horizontal movement in the soil, one cannot but wonder how a seed applied insecticide will protect the roots several inches away. The company explanation is that the patented process of micro-encapsulation and polymers gets it there. Seed treated with tefluthrin will probably be well protected from secondary insects, though there is little to no data to support this.
We are excited about the possibility of getting soil insect control using 40% of the active ingredient in a granular insecticide. As well, producers will likely welcome the convenience of applying a soil insecticide in this fashion. We look forward to sharing more information about this product from the 2000 growing season in future issues of the Pest&Crop.
Federal approval of the following herbicides is anticipated before the start of the growing season.
Extreme – (labeled for 2000)
Domain – (labeled for 2000)
Degree Extra – (labeled for 2000)
Ready Master ATZ – (anticipated label in 2000)
Uniform stands of corn are important for achieving full yield potential from those bags of expensive seed corn that you buy and plant. Uneven plant-to-plant spacing and/or emergence can reduce yield potential by seven to 15 bushels per acre, with little hope of ever recovering that difference by the end of the growing season.
After planting is completed...
Much of Indiana has received less than normal rainfall since mid-summer 1999. Soil moisture reserves are currently very low, especially in the northern half of Indiana. Some forecasters are predicting widespread drought for this coming growing season. What plans, if any, should Indiana corn and soybean farmers develop to manage the effects of a possible drought in 2000?
Yes, we are dry ...
As of 22 February, the National Drought Mitigation Center (http://enso.unl.edu/monitor/monitor.html) characterized much of the northern half of Indiana as being in a Level 2 or severe drought stage (level 4 being the worst). Numerous reports have been received (post hole digging, grave digging, tile repair) testifying to the dryness of the subsurface soils throughout much of the area. Precipitation for the past nine to twelve months has been below normal.
But, the outlook is not exactly droughty ...
Fortunately, current long-range weather forecasts from the NOAA Climate Prediction Center (http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/page3.gif ) are not particularly dry in their predictions for precipitation for our area of the Corn Belt through early to mid-summer. Granted, none of the monthly forecasts are predicting above normal rainfall, but few are calling for significant chances of below normal rainfall either. Nonetheless, some private forecasters are predicting strong probabilities for a major drought occurring somewhere in the Corn Belt this coming crop season. Those forecasts plus the current dry subsoil situation throughout northern Indiana are making quite a few farmers nervous about the prospects for drought stress on corn and soybeans in 2000.
Planning for drought ...
Planning for drought stress is not necessarily a smart move for Indiana corn and soybean growers. Historically, the odds are in our favor for sufficient rainfall to grow crops. Planning for drought is somewhat like planning to fail. Nonetheless, there are a few agronomic options available for those bent on planning for a drought.
Tillage operations …
Minimize the number of tillage operations you plan on performing on your fields yet this spring. Reducing tillage trips will lessen the opportunity for further evaporative soil moisture loss. An added benefit is that your overall fuel expense will also decrease. Where soils are suitable or adaptable (moderate- to well-drained), consider foregoing tillage altogether and implementing a no-till cropping system instead. Crops will benefit later in the season from conserved soil moisture.
Variety selection ...
By now you should have been working closely with your seed dealer to identify high-yielding varieties with excellent drought tolerance, early season vigor and stable yield performance. High population tolerance is often related to drought tolerance and thus can be used as an indirect indication of drought tolerance in a hybrid. Early season vigor is important for encouraging healthy, vigorous stands of corn or soybean that will better tolerate stresses later in the season. Stable yielding ability means the ability to yield at a relatively constant level no matter the growing conditions. Corn hybrids that are bin-busters in excellent weather, but fall apart under stress are not the hybrids of choice if drought is looming in your future.
Seeding rate selection …
Many factors influence the choice of the “correct” seeding rate for corn hybrids. Generally speaking, hybrids with small crop canopies, good to excellent stalk health characteristics and little ear size flexibility perform best at higher seeding rates. Conversely, hybrids with large crop canopies, average to poor stalk health characteristics and significant ear size flexibility do not require as aggressive a seeding rate.
Seeding depth ...
If seedbed conditions are dry at planting time, then your main objective should be to place the seed in uniformly moist soil. If necessary, corn can be planted as deeply as 3 inches if that is the depth where seedbed moisture is uniform. Soybean, on the other hand, should not be planted much deeper than 1 inches deep because of the difficulty created for the emergence of the hypocotyl or “shepherd’s crook” of the seedling.
Seeding into a dry seedbed ...
If soil is bone-dry at planting, but you anticipate rainfall in the near future, go ahead and plant. Recognize that seed stores as well in a dry seedbed as in a dry seedbag! Those of you that experienced the “Great Drought of 1988” should remember those fields planted in late April that finally germinated and emerged perfectly in late July once enough rainfall occurred. Insect and disease activity are generally less in dry soils. Having the seed already planted also avoids further planting delay after rain does occur.
Planting date ...
Early planting helps avoid the usual summer heat and dry stress conditions during flowering, especially for corn. In fact, this factor was one of several that helped the 1999 corn crop in Indiana yield as well as it did given the dryness and several hot spells that much of the state endured. So, be well prepared to head for the fields as soon as the soil is fit and temperatures are reasonable. Historically, those conditions occur from about early April in southern Indiana to late April in northern Indiana.
Fertilizer N decisions ...
If you feel strongly that a major drought is imminent and your corn crop will suffer severely, then consider hedging your nitrogen bets by foregoing pre-plant nitrogen fertilizer in favor of sidedress N applications. Apply 20 to 40 lbs. N in your starter fertilizer. Assess crop condition prior to sidedress time. If the crop is struggling with drought stress, you may opt to apply less N at sidedressing if you anticipate significant yield decreases due to drought. In the worst case scenario, you may opt to not apply any further N if the crop is heading toward total disaster. On the other hand, remember that a rainy June may create problems for you in terms of covering all of your corn ground at sidedressing time.
Irrigation issues …
Corn requires from 16 to 25 inches of water (rain, irrigation, & soil) to produce a crop of grain. Critical times for avoiding water deficits are stand establishment (emergence to knee-high), determination of potential ear size (knee-high to shoulder-high), pollination and the grain filling period. Of these time periods, drought stress at pollination can impact grain yield the most. Maximize irrigation efficiency by matching irrigation use with rainfall and crop demands. Minimize costs and maximize yields by implementing formal irrigation scheduling procedures. A comprehensive Web site on numerous irrigation issues is available at the University of Nebraska-Lincoln (http://www.ianr.unl.edu/pubs/irrigation/).
Historically, drought is not something folks should generally plan for in the eastern Corn Belt. Implement sound agronomic strategies to encourage a vigorous crop and aim for “normal” yields, but adjust for soil and crop conditions where feasible.